Stock lens minimum focus limit??

[Chris Harding]

Hi Guys

Any idea of what the minimum focus distance the stock 18-200 has at 18mm?? I usually use my Tokina 11-16 to do guest interviews where I'm pretty close to the person so I can use the on-camera shotgun for audio but on Saturday I got lazy and used the stock lens and quite a few guest congratulations had the auto focus struggling to lock on!! With the Tokina I can actually cheat and leave the focus preset at 2.5' and at 11mm it's in focus from 2' right out to 10' .... Using the DOF calculator the stock lens if your subject is 6' away your DOF is from 4.5' to 9' at F3.5 so I expect the AF to be able to lock in focus.

Anyone had AF focus issues when you are 6' or less away from someone??? I'm wondering if the lens has a minimum limit??

Chris

[Steven Digges]

Hi Chris,

I can't give you the exact number your looking for because I have not tested for it yet. Remember your DOF chart is a guide, it will vary some from one lens to the next.

So far I have been very impressed by the kit lens close focus ability. It is almost macro, so I don't think distance was your AF problem. Were you in a dimly lit reception hall? My guess is low light? The AF does respond much better in good light.

A couple months ago I shot live dental surgery. I went into the shoot thinking I would use my Canon 24-70 2.8 L Macro lens. Once on site I ended up using the stock lens because I COULD get the tight shot I needed of just the patients mouth and teeth. The camera was on my crane hovering over the patient. Of course I used manual focus for something that critical and it looked great. Using the kit lens gave me an advantage over the Canon because I could zoom out with the remote to get more of the face when I needed to. I was very pleased with its focus distance.

I'm sure you know this but I will comment on it anyway so no offence. The difference between 11mm and 18mm is HUGE. They are a world apart. At long telephoto ranges over 200mm a 7mm difference is almost imperceptible. At the wide angle end of the spectrum every MM is a big change. You can't expect an 18mm lens to perform in the same ballpark as an 11mm.

To know the focus distance, DOF, and AF performance of the kit lens at 18mm you will have to test it taking real shots. I don't think charts or specs will help you as much as looking at film you shoot.

Steve

[Noa Put]

I also think the lens had issues locking on because it might have been too dark or it might have been fooled by a bright object in the frame, I have experienced this shooting in bright daylight when the groom's car (a oldtimer) arrived, the car had a very shiny and reflective paint and it threw the autofocus off completely, just another example what can happen if you let the camera make decisions for you. Just focus manually and the problem is gone.

[Chris Harding]

Thanks Guys

I use the Tokina 11-16 for guest interviews as it has a huge DOF at 11mm so I'm in focus 99% of the time without having to change the focus ring from the last person and it's pin sharp too.

Yeah I think it's purely the fact that AF didn't have enough contrast to work with.

Just for interest what is a good lens apart from the stock lens for super closeups?? Bear in mind I'm using Nikon mounts ..haven't been asked to do any extreme macro shots yet but it could happen.

Chris

[Steven Digges]

I was one of thousands of sports photographers that switched from Nikon to Canon in the early ninety's. The last time I took a macro shot with a Nikon there was a bellows tube on it! Sorry Chris, can't help you there :) :) : )

Steve

[Noa Put]

Don't know if sony has any nex macro lenses? But I guess any macro lens with the appropriate adapter would do.

[Chris Harding]

No big deal

I have yet to be asked to film a busy any farm colony for a documentary so it's not really important!!

As Noa says any manual macro lens will work ... you certainly wouldn't need AF going ultra close anyway!

Chris

[Steven Digges]

Hey Chris,

I came across specs for the stock lens. The minimum focus distance is listed as 1.0' (30.48 cm).

Steve

[Chris Harding]

Thanks Steve

In that case I was only around 6' away from people and the AF was definitely struggling to lock on to peoples faces so it is indeed very slow in lower light and closeups where it needs to snap into focus quickly and wasn't anywhere near it's limit.

Doing quick congratulations at wedding receptions means switching to different faces in rapid succession as they clamour to say their bit and it's not a good scenario for the stock lens AF. Using my super wide and just setting the focus to around 3' or 4' works really well and allows me to work like a point and shoot camera as the DOF is huge at 11mm and I rarely need to trim the focus ring.

The AF at "normal" distances in good light is pretty good though and my usual operation is to let AF do the work until focus peaking shows me what is in focus then I switch to manual so the AF cannot decided to change to something else in the background.

Chris

[Steven Digges]

At 11mm you should be on their face like a huge pimple ;) I know you know your 50s inside out. For the AF scenario you are describing that is what the AF "button" is for. You run in manual focus and push the button to pull a AF focus. I have been working with cameras that have that function for years. I love it.

My experience with the kit lens is, I find it a little slow to lock on, but when it does it holds very well. I went through the entire series of Canon XL cameras beginning with the XL1 on through the HD cams. One of their big weaknesses was AF. It would search and fail so fast and keep searching until it kicked your but and ruined the shot. Even though they were f2 (in some cases) the manual focus sucked too because of the servo.

For a servo lens combined with the amazing peaking the EA50 focuses well manually too. Relatively speaking. The AF just needs a lot of light. Again, I know I'm not telling you anything but we seem to have a few new guys feeling their way around the camera. The guy that bought Noa's should have required Noa to give him six months of one on one training!

I run peaking on medium yellow and use the assign button to get it off the view finder if I don't want to see it. The reason I call the peaking amazing is it seems to be accurate through the entire DOF. That is not always the case with peaking. I have learned to trust this one.

Some kit lenses are junk. Yes this a slow lens, both in aperture and zoom speed, but given enough light, I think you and I both agree that this is a pretty damn good lens for what it is. I have the kit lens for convenience and my quiver of Canon "L" series lenses for much of what I do. Thats why I chose the EA50 last year.

Steve

[Chris Harding]

Hey Steve

That is quite correct ..once it locks on it's really good but it does take a few seconds and when I have people crowding around me saying "I want to say something" I need instant focus as I try to accommodate them all while they are willing. With the crop factor 11mm on the Tokina is quite usable and I can stay close to each person so I get great audio from the shotgun as it's only 3' away !

I actually bought the 11-16 for Realty shoots and Realty photography where the agents want wide coverage! and I found with either a prime or stock lens the AF failed miserably when I was filming white walls and moving to white ceiling as there is just not enough contrast for the AF to work so that's done with preset focus and works really well too (these are rental condition reports not "for sale" videos)

I had one instance with the AF at a wedding where the camera decided that the pots and pans in the café behind the bride was the place to focus rather than their faces so that was a little soft. That's why I setup in auto, and like you use yellow/medium peaking, then when I'm happy that the camera is locked on the couple, I switch the AF to manual so it's locked... they seldom move much but if they do then I'll use the push to focus button ... I think I don't ever turn peaking off actually ... you get used to everything covered in yellow dots and lines but at least you are getting a constant confirmation of focus.

Chris

[Peter Rush]

Originally Posted by Steven Digges

Some kit lenses are junk. Yes this a slow lens, both in aperture and zoom speed, but given enough light, I think you and I both agree that this is a pretty damn good lens for what it is. I have the kit lens for convenience and my quiver of Canon "L" series lenses for much of what I do. Thats why I chose the EA50 last year.

Steve

Ditto - the kit lens for me is more than adequate if there's enough light, and slap on a ND filter and it's good to go in sunlight without crazy shutter speeds.

Peaking is very good with all my lenses apart from my wides like the Samyang 14mm or Sony pancake - it's a little hard to judge on the EA50 (and on my VG20 which has the same type of peaking) with these but DOF is pretty deep with these wide lenses so is hard to get it really wrong.

Pete